Isozyme Loci Research Articles

Особенности генетической структуры популяции Pinus sylvestris L. в степной зоне Европейской России

The article presents the results of studу of the genetic structure of Scots pine (Pinus sylvestris L.) growing in the ecologically favorable territory of the steppe zone of European Russia. 35–year-old pine forest plantations (the Voronezh Region, Kantemirovskiy District, the 3rd bonitet class, forest site type – A1, a random sample, 60 trees) have been chosen as the object of the study. Genetic diversity has been examined on the basis of the microsatellite analysis of 18 SSR-loci (14 EST-SSR-loci and 4 nSSR-loci) and two isozymic loci (shikimate dehydrogenase and glutamate dehydrogenase – or Skdh and Gdh, respectively). It has been revealed that in the studied population, all the used microsatellite loci, with the exception of lw_isotig02842, are polymorphic. The average values of genetic variability calculated from the microsatellite loci have been obtained: the proportion of the polymorphic loci – 94.44 %, the average number of alleles per locus – 3.500, the average effective number of alleles – 2.466, the observed and expected heterozygosity – 0.209 and 0.493 respectively; the Wright fixation index – 0.577. In terms of the level of allelic diversity, the plantation is characterized by relatively lower values of genetic and statistical population parameters (the average observed and expected heterozygosity) compared to the natural forest-steppe populations of the Central Chernozem Region. A high positive Wright fixation index indicates the presence of an increased proportion of inbreeding in the steppe population trees. The reasons and possible nature of the revealed phenomenon are discussed. Based on the isoenzyme analysis, the genetic structure of the Skdh and Gdh loci is examined. The results of the analysis indicate a high frequency of the rapid allele Skdh-11 (82 %) and the embryonic semi-lethal allele Gdh-11 (22 %), which, apparently, can be considered as one of the mechanisms of the population adaptation to the conditions of a warmer and drier climate of the steppe region. A deficiency of glutamate dehydrogenase heterozygotes has been established. It has also been noted that the groups of EST-SSR-loci and nSSR-loci differ in the level of genetic variability and population structure. It has been shown that the combined use of different types of genetic markers makes it possible to obtain more complete and objective information on the distinctive features of the genetic structure of pine forests in the optimal and pessimal zones of the range. The studied 18 microsatellite loci can be used to assess the genetic diversity of Scots pine populations and trees in the steppe region of European Russia.

The allopolyploid origin of <i>Euphorbia stevenii</i> and <i>E. boöphthona</i> (Euphorbiaceae)

To elucidate the ancestry of the allopolyploids <i>E. stevenii</i> and <i>E. boöphthona</i>, I examined eleven isozyme loci and 24 morphological characters from 28 populations representing five related <i>Euphorbia</i> species from Australia. According to an analysis of genetic and morphological data, three diploid species differentiated recently, but two independent polyploid species are estimated to have differentiated a relatively long time ago. Fixed heterozygosity for most isozymes in <i>E. stevenii</i> and <i>E. boöphthona</i> strongly suggests that these two species are allopolyploids rather than autopolyploids. The isozyme profiles of <i>E. stevenii</i> indicate that it is an allopolyploid that evolved from interspecific hybridization between the diploid <i>E. tannensis</i> and unidentified or extinct tetraploid species. In addition, isozyme patterns strongly suggest that <i>E. stevenii</i> was one of the ancestors of <i>E. boöphthona</i>. However, <i>E. boöphthona</i> showed a large number of fixed alleles that were not detected in any other Australian <i>Eremophyton</i> species. The most likely hypothesis for the origin of <i>E. boöphthona</i> is that it was formed by hybridization and chromosomal doubling between an extinct diploid species and the hexaploid <i>E. stevenii</i>.

Genetic diversity and relationship between wild and cultivated cowpea [Vigna unguiculata (L.) Walp.] as assessed by allozyme markers

Abstract In Cameroon, cowpea plays an important role in traditional agroecosystems. Genetic variation in wild and cultivated cowpea in Cameroon has not yet been documented. Allozyme markers because of their codominance and polymorphism are useful tools for studying genetic variation and disparity in plant species. The present study was undertaken to elucidate the relationship between wild and cultivated cowpea from Cameroon. Ten enzyme systems encoding nineteen isozyme loci were used on 62 cowpea germplasm (45 wild and 17 cultivated). A total of thirty-two alleles were found. One allele was only found in cultivated samples (Enp98 ). Eight alleles were specific only to wild plant (Amp2 98 , Amp3a 103 , Amp4 96 , Fdh104 , Idh2 95 , Pgi3 92 , Pgm2 95 and Sdh95 ). Twenty-three alleles were common to both wild and cultivated accessions. Amp2 10 2 (z = −4.633, p < 0.001) and Fle3 96 (z = −2.858, p < 0.010) were significantly more represented in cultivated compared to wild cowpea forms. The mean number of alleles per locus in wild (1.632 alleles/locus) cowpea were significantly higher (t = 2.805, p < 0.010) compared to cultivated (1.263 alleles/locus) cowpea. Also, the proportion of polymorphic loci (P = 52.63%) and average Nei’s genetic diversity (He = 0.126) were important in wild, compared to the cultivated plants: P = 26.31% and He = 0.063, respectively. The low level of diversity found in domesticated accessions compared to wild can be attributed to a major genetic bottleneck that probably happened during the domestication process. Cluster analysis revealed by UPGMA dendrogram separated the 62 accessions into three clusters. Although an admixture of both wild and cultivated accessions within the same cluster were found, the dendogram, however, highlighted a visible separation between wild and cultivated cowpea. Wild cowpea with many more private alleles indicates an untouched resource available for future breeding.

The consensus rye microsatellite map with EST-SSRs transferred from wheat.

Microsatellite (SSR) markers with known precise intrachromosomal locations are widely used for mapping genes in rye and for the investigation of wheat-rye translocation lines and triticale highly demanded for mapping economically important genes and QTL-analysis. One of the sources of novel SSR markers in rye are microsatellites transferable from the wheat genome. Broadening the list of available SSRs in rye mapped to chromosomes is still needed, since some rye chromosome maps still have just a few microsatellite loci mapped. The goal of the current study was to integrate wheat EST-SSRs into the existing rye genetic maps and to construct a consensus rye microsatellite map. Four rye mapping populations (P87/P105, N6/N2, N7/N2 and N7/N6) were tested with CFE (EST-SSRs) primers. A total of 23 Xcfe loci were mapped on rye chromosomes: Xcfe023, -136 and -266 on chromosome 1R, Xcfe006, -067, -175 and -187 on 2R, Xcfe029 and -282 on 3R, Xcfe004, -100, -152, -224 and -260 on 4R, Xcfe037, -208 and -270 on 5R, Xcfe124, -159 and -277 on 6R, Xcfe010, -143 and -228 on 7R. With the exception of Xcfe159 and Xcfe224, all the Xcfe loci mapped were found in orthologous positions considering multiple evolutionary translocations in the rye genome relative to those of common wheat. The consensus map was constructed using mapping data from the four bi-parental populations. It contains a total of 123 microsatellites, 12 SNPs, 118 RFLPs and 2 isozyme loci.

Analysis of genetic diversity in oilseed brassica germplasm through ISSR markers and isozyme profiling

Eleven Brassica germplasm were characterized through the application of 12 oligonucleotide Inter Simple Sequence Repeat (ISSR) primers. A total 1248 bands were amplified through polymorphic chain reaction and were visualized by agarose gel electrophoresis. Among the amplified marker bands 71.47% were polymorphic in nature and 352 bands were found to be monomorphic. The polymorphic bands of the amplified DNAs mostly ranged between 110 bp and 3 kb. Genetic distance among the germplasm ranged between 0.0468 and 0.7189. Moreover, three isozyme systems such as esterase, acid phosphatase and peroxidase were analyzed for allozyme variability that detected distinct 93 isozyme loci of which nearly 61.9% were polymorphic. Two dendrograms were constructed based on the ISSR profiling and isozyme data obtained through electrophoresis to find out the relatedness and phylogenetic relationship among the investigating Brassica germplasm. The clusters of the phylogenetic tree revealed 4 distinct groups of Brassica based upon their ISSR banding patterns and isozyme analysis. Nei’s genetic distance analysis provided strong information about the existence of variability among the germplasm of Brassica. All the germplasm was found to be clustered according to their respective species. Brassica carinata (Ethiopian mustard) showed individuality from all the germplasm studied and made a different branch in the phylogenetic tree suggesting its diverse origin. From the clustering pattern and genetic relationship obtained with ISSR markers and isozyme analysis, breeders can successfully identify the diverse germplasm from different cluster and use them in their future breeding program.

Genetic variability of Anthoxanthum aristatum Boiss. (Poaceae) at the non-native range limit

Anthoxanthum aristatum Boiss. is native to southern and western Europe and North Africa. In Central Europe this species is recognized as invasive. Its ability to colonize various habitats may result from a high level of polymorphic isozyme loci and high morphological variability. The aim of this study was to recognize the degree of genetic diversity of the studied invasive species at its non-native range limit using molecular markers. The examined plant material consisted of 70 samples collected from 7 populations originating from various habitats: arable fields, recently abandoned field and sandy grassland. Ninety-six the Directed Amplification of Minisatellite-region DNA loci and 82 Sequence-Related Amplified Polymorphism loci were detected. The genetic diversity at the species level was high. The majority of genetic variation was present within populations (68% and 66%), while the remaining molecular variation was distributed among populations within and among habitat types. Specimens originating from sandy grassland populations were grouped together in one cluster that was genetically distinct from the arable field and fallow populations. The high genetic diversity populations at the A. aristatum non-native range limit in Central Europe and their marked diversity in arable field and sandy grassland habitats suggest that this species may systematically cross both geographical and ecological barriers.

Hybridization in wild pear (Pyrus pyraster) from various regions in Germany and from Luxembourg with respect toPyrus×communis

Pyrus pyraster is the prevailing native pear species in central Europe. The range of this forest tree species is comparatively large within the temperate zone. In most regions wild pear is very rare and considered to be seriously endangered. Thus, conservation of P. pyraster as part of the natural biodiversity is essential. The species may serve as a genetic resource in breeding programs, e.g., use of resistances existing in a wild species. A precondition for suitable conservation and breeding strategies is the identification of pure wild pears. Introgression from cultivated pears, supposed to be one major threat to the native gene pool, needs to be investigated. In total, 636 genotypes of P. pyraster and P. × communis were analysed. The 316 trees initially selected as P. pyraster originated from Germany (242) and Luxembourg (74). Pear trees growing in Germany belonged to populations in the states Rhineland-Palatinate (101), Saxony-Anhalt (120) and Saxony (21). A total of 320 cultivars, separated into old (238) and modern (82) categories, were provided by collections in Germany and Oregon/USA (NCGR, Corvallis). Accessions have been typed for eight polymorphic isozyme loci. A model-based Bayesian clustering approach was applied to all multilocus genotype data. Wild and cultivated pear trees made up two different gene pools but could not be distinguished very clearly by nuclear markers. However, modern cultivars appeared to be distinct from all other subgroups. The discrimination between 'wild' and 'cultivated' was less obvious than in European apples. The genetic result might be expected when following the evolutionary hypothesis that P. pyraster is one primary progenitor of European cultivars. Morphologically wild pears from natural sites and old cultivars looked quite different. The extent of hybridization between the two major gene pools investigated is hard to assess.

Analysis of Changes in the Genetic Structure of Chronically Irradiated Scots Pine Populations

Data about the long-term effects of the chronic radiation exposure of forests to the radioactive trail of the Chernobyl disaster are insufficient. The method of vertical electrophoresis in PAAG is used to estimate the polymorphism of enzymes in Scots pine populations growing on the territory of Bryansk oblast, which was contaminated with radionuclides. The activity of enzymes in Scots pine seeds is estimated by spectrophotometry. The overall frequency of mutations in the isozyme loci increases with the dose rate of chronic irradiation (7–130 mGy/year), as well as some characteristics of the genetic structure of the populations. The activity of enzymes does not depend on the level of the dose absorbed by the generative organs of pine. The impact of radiation contributes to changes in the genetic structure of Scots pine populations.

Regional climate oscillations and local topography shape genetic polymorphisms and distribution of the giant columnar cactus Echinopsis terscheckii in drylands of the tropical Andes

AbstractAimWe sought to determine if the present fragmentary distribution of the giant columnar cactus Echinopsis terscheckii in tropical drylands is a relict of a previously more widespread range during cold and dry phases of the Last Glacial Maximum (LGM).LocationTropical and subtropical dry ecotonal areas of northern and central Andes of Argentina.MethodsWe combined ecological niche models (ENM) with molecular polymorphisms of isozymes and DNA sequences. We collected samples from 30 individuals at 24 locations for genetic analysis covering a wide range of environmental conditions. We sequenced the nuclear ITS and three non‐coding regions of the chloroplast DNA and we resolved 15 isozyme loci. Potential distribution was modelled using 88 E. terscheckii presence training records and a reduced set of 10 modern bioclimatic variables. LGM and the Mid‐Holocene distributions were derived by projecting bioclimatic data under present to past environmental conditions according to CCSM4 and MIROC‐ESM Global Climate Models.ResultsWe detected high isozyme diversity towards the south. The multivariate cluster analysis yielded two groups of populations that were geographically concordant with the DNA haplotypes located north and south of a divide at 27°S. Distribution models show range expansion during the LGM in two north and south areas separated by a gap of low suitability at 27°S. Suitable areas in the south were close to current populations, while in the north, populations survived in more disjunct locations that probably suffered from founder effects. In contrast, Mid‐Holocene bioclimatic conditions were relatively unsuitable in the south.Main conclusionsOur results suggest that the divergence of north and south groups of E. terscheckii populations reflect long‐lasting persistence through climatic cycles that were reinforced by the presence of an orogenic divide at mid‐latitudes. Latitudinally divergent groups of populations should be treated as distinct evolutionary significant units that deserve independent conservation actions. Increased genetic diversity and inbreeding towards the south may guide setting up priorities for the long‐term protection of a dominant element of drylands as E. terscheckii.

The reasons of genetic heterogeneity of Siberian whitefish Coregonus lavaretus pidschian in the Anabar river

Background. A population genetic study of Siberian whitefish or pidschian Coregonus lavaretus pidschian Gmelin of the Anabar River (North-West Yakutia) has been done to study genetic structure of the species within a river system and for revealing its phylogeographic relations.
 Materials and Methods. Five samples of pidschian from different parts of the river were analyzed for 30 isozyme loci.
 Results and Discussion. The results has demonstrated a significant genetic heterogeneity of the species sampled from lower and middle reaches of the river (0.001 DN 0.056). The most likely reason for genetic differentiation of the species within the river system is a colonization of the watershed by independent phylogenetic lineages of whitefish. At present the phylogenetic lineages in Anabar River are presented by sympatric ecological forms of the species eastern-siberian whitefish and glacial-plains whitefish which maintain their reproductive isolation. The relationships of ecological forms of whitefish dwelling the Anabar River with other populations of the species in Siberia, and possible ways of penetration of discrete phylogenetic lineages of pidschian in the basin of studied river are discussed.
 Conclusions. A genetic heterogeneity of whitefish from Anabar River should be taken into account while creating adequate intraspecific taxonomy and considered in conducting fisheries and environmental measures.

Absence of an acid phosphatase isozyme locus as a marker candidate for true to typeness in woodland grape (Vitis vinifera L. ssp. sylvestris Gmelin)

<p style="text-align: justify;">The quest and conservation of existing populations of woodland grape (<em>Vitis vinifera</em> L. ssp. <em>sylvestris</em> Gmelin), the supposed progenitor of the European grapevine (<em>Vitis vinifera</em> L. ssp. <em>sativa</em>) and a significant actor in the evolution of grapevine, has great importance in preserving biodiversity. The proof of true-to-typeness is highly important in ex-situ conservation, because the contamination risk of the woodland grape populations is very high. Some characteristic “<em>sylvestris</em>” simple sequence repeats (SSR) alleles were identified, but they are only characteristic in a specific population.</p><p style="text-align: justify;">In our recent study, the SSR profiles of 32 woodland grapes were compared to those of 16 European grapevine varieties and 20 rootstocks. Morphology and SSR analyses suggested that the analysed <em>Vitis vinifera</em> ssp. <em>sylvestris</em> Gmelin accessions were true-to-type. In this report, the results of the acid phosphatase isoenzyme analyses of the same woodland grape accessions are presented and a new marker for true-to-typeness is suggested.</p>

Genetic variation of silver fir progeny from Tisovik Reserve population determined via microsatellite and isozyme markers

Abstract Progeny from 19 family lines of silver fir (Abies alba Mill.) from a small, native and isolated population from the Tisovik Reserve (Belarusian part of Białowieża Primeval Forest) growing in an experimental plot near Hajnówka (Polish part of Białowieża Primeval Forest) were analysed in terms of 4 nuclear microsatellite DNA loci and 9 isozyme systems with 14 loci. The aim of this study was to determine the genetic variation within and between progeny lines. Analysis of isozyme loci showed that all progeny lines, except the progeny lines T6 and T16, were characterised by an excess of heterozygotes and 20% of the detected variation occurred between progeny. Progeny formed two groups. Microsatellite loci showed that 6 progeny lines demonstrated an excess of heterozygotes and 12 an excess of homozygotes. On an average, the population was in the Hardy-Weinberg equilibrium. Analysis of molecular variance (AMOVA) showed that 14% of the detected variation occurred between offspring and the remaining 86% within progeny lines. The most distinct progeny line was Tl, where the highest number of alleles per locus was detected. Generally, progeny of Tisovik is characterised by high level of differentiation as the offspring of isolated population that have limited number of individuals to crossing (only 20). In some progeny line, the private alleles that are detected may be the result of pollination from Polish part of Białowieża Forest where in 1920s and 1930s of XX century had planted the seedling of silver fir of unknown origin. The substructuring of population is observed, and the detected deficiency of heterozygotes may be ostensible as a result of the Wahlund effect. Such pattern of genetic structure could also be an effect of harsh environmental conditions exerting selection pressure and modifying the genetic composition of this population.

Disequilibrium distribution of genotypes in the pairs of isozyme loci in the pine populations of the forest-steppe regions of Siberia

We performed an analysis of linkage disequilibrium of alleles of 15 allozyme loci in 35 populations of Scots pine in the Siberian part of the range between 50° and 56° N and 79° and 107° E. We found a significant deviation in the distribution of genotypes of 1–9 pairs of loci in the investigated samples. We established correlations between frequencies of certain pairs of linked loci with ecological conditions and geographical coordinates of habitats of the pine populations. We present the results of comparative analysis of the differences in certain morphological features of trees with significantly predominant genotypes for pairs of linked loci in three isolated populations: in the south of Krasnoyarsk krai, Khakassia, and Tuva.

Retracted: Flavonoid-Deficient Mutants in Grass Pea (Lathyrus sativus L.): Genetic Control, Linkage Relationships, and Mapping with Aconitase and S-Nitrosoglutathione Reductase Isozyme Loci.

[This retracts the article DOI: 10.1100/2012/345983.].

Genetic studies revealed differences between European and North American populations of Calypogeia azurea

Abstract Calypogeia azurea, a widespread, subboreal-montane liverwort species, is one of a few representatives of the Calypogeia genus that are characterized by the occurrence of blue oil bodies. The aim of the study was to investigate the genetic variation and population structure of C. azurea originating from different parts of its distribution range (Europe and North America). Plants of C. azurea were compared with C. peruviana, another Calypogeia species with blue oil bodies. In general, 339 gametophytes from 15 populations of C. azurea were examined. Total gene diversity (HT) estimated on the basis of nine isozyme loci of C. azurea at the species level was 0.201. The mean Nei’s genetic distance between European populations was equal to 0.083, whereas the mean genetic distance between populations originating from Europe and North America was 0.413. The analysis of molecular variance (AMOVA) showed that 69% of C. azurea genetic variation was distributed among regions (Europe and North America), 15% - among populations within regions, and 16% - within populations. Our study revealed that C. azurea showed genetic diversity within its geographic distribution. All examined samples classified as C. azurea differed in respect of isozyme patterns from C. peruviana.

DIVERSITY AND GENETIC STRUCTURE OF NATURAL POPULATIONS OF ARAÇÁ (Psidium guineense Sw.)

ABSTRAT: Psidium guineense Sw, popularly known as araçá, is a fruit tree there is widely distributed in Brazil and belongs to the Myrtaceae family. In northeastern Brazil, araçá occurs along coast and in the Zona da Mata; its fruit looks like guava but is more acidic and has a stronger smell. There is a little information about this species, which increases the difficulty of conserving its genetic resources and exploiting araçá as an economic resource. The objective of this research was the evaluation of the genetic diversity and genetic structure of P. guineense from Pernambuco's Zona da Mata. One hundred and fourteen individuals and 18 isozyme loci were evaluated, showing 28 alleles. The percentage of polymorphic loci () and the average number of alleles per locus () were 0.5 and 1.5, respectively, in this population. The expected heterozygosity, which corresponds to the genetic diversity, ranged from 0.22 to 0.23, a high value when considering that isozymes mark access from the functional genome. The differentiation index among the population was () = 0.015; therefore, the populations were not different among the sampled places. The inbreeding values () ranged from -0.549 to -0.794, indicating an absence of inbreeding and a greater-than-expected heterozygosity in all the studied populations. The estimated gene flow (Nm) for a pair of this population ranged from 3.23 to 20.77, sufficient to avoid genetic differentiation among the population and in accordance with the values of genetic divergence found in this study.

Diversity evaluation based on morphological, physiological and isozyme variation in genetic resources of garlic (Allium sativum L.) collected worldwide.

The aim of this study was to obtain primary information about the global diversity of garlic (Allium sativum L.) by evaluating morphological, physiological and isozyme variation. A total of 107 garlic accessions collected worldwide were grown in Yamaguchi, Japan. Five morphological traits (bulb weight, bulb diameter, number of cloves per bulb, number of bulbils and scape length) and one physiological trait (bolting period) of the collected garlic showed wide variation. Meanwhile, a total of 140 garlic accessions, including the 107 mentioned above, were characterized by leucine aminopeptidase (LAP) and phosphoglucoisomerase (PGI) isozyme analyses; they clearly showed polymorphisms in putative isozyme loci (Lap-1, Lap-2 and Pgi-1). Allelic frequencies were estimated in each group of accessions categorized by their geographical origin, and the observed (Ho) and expected (He) heterozygosities were calculated. The allelic frequencies differed between groups. A principal component analysis based on morpho-physiological data indicated a grouping of the garlic accessions into Central Asian and Northern Mediterranean groups as well as others. We discuss the roles of artificial and natural selection that may have caused differentiation in these traits, on the assumption that ancestral domesticated garlic populations have adapted in various regions using standing variation or mutations that accumulated during expansion, and have evolved along with human-preferred traits over a long history of cultivation.

Identification of complementary genes of hybrid lethality in crosses of bread wheat and rye. Results and perspectives

Numerous genes were found in crop plants, leading to death or sterility of distant hybrids. However, the evolutionary role of concrete genes in the reproductive isolation of the species remains unclear. The article summarizes the own data for identification of hybrid lethality genes that were detected in wheat -rye crosses. Seeds with the dead, undifferentiated embryo and normal endosperm were found in crosses of bread wheat with four out of a hundred studied inbred lines of rye. It is shown that the hybrid lethality is a consequence of the negative complementary interaction of genes of wheat and rye. Rye gene Eml-1R is represented by two alleles - dominant incompatible and recessive compatible. It was mapped on chromosome 6R relative microsatellite and isozyme loci. Complementary wheat gene Eml-1A is located on chromosome 6A. Location of interacting genes on syntenic fragments of chromosomes 6R and 6A may indicate gomeology of hybrid lethality genes in wheat and rye. However, embryonic lethality observed in individual wheat-rye hybrids, cannot be attributed to the evolutionary developed intergeneric incompatibility, like a well-studied prezygotic incompatibility of wheat and related genera.

Defining Genetic, Taxonomic, and Geographic Boundaries Among Species of the Psorophora confinnis (Diptera: Culicidae) Complex in North and South America.

The Psorophora confinnis complex is currently composed of three species--Psorophora confinnis sensu stricto (Lynch Arribalzaga) in South America, Psorophora columbiae (Dyar and Knab) in North America, and Psorophora jamaicensis (Theobald) in the Caribbean. Members of the complex are of considerable importance as vectors of arboviruses, for example, Venezuelan equine encephalitis virus, and are significant biting pests throughout their range. The biological and geographic boundaries of Ps. confinnis and Ps. columbiae are unclear. In fact, the name Ps. columbiae is presently designated as "provisional." In this article, we aim to clarify the taxonomy and geographic distributions of species within the Ps. confinnis complex. A population genetics approach was employed using gene and genotypic frequency data at 26 isozyme loci. The results suggest that the Ps. confinnis complex in North and South America is composed of four species. Ps. confinnis s.s. and Ps. columbiae are distinct species in South and North America, respectively. Populations in Colombia, South America, formally designated as Ps. funiculus (Dyar) and populations in the southwestern United States and western Mexico, formally designated Ps. toltecum (Dyar and Knab), are distinct species. Psorophora toltecum and Psorophora funiculus species names should be resurrected from synonymy. In addition we identified a Ps. columbiae and Ps. toltecum hybrid zone in central Texas in a region described as being one of 13 North American suture zones, being geographical areas in which closely related species occur in sympatry and frequently hybridize.

Genetic variation and differentiation among populations of <i>Euphorbia ebracteolata</i> (Euphorbiaceae) in Korea

ABSTRACT: Using starch gel electrophoresis, ten isozyme loci were examined in nine populations of Euphorbiaebracteolata in Korea. Populations of E. ebracteolata tend to have higher within-population levels of geneticvariation (A = 2.2, P = 61.1, He = 0.165) along with low levels of genetic differentiation (F ST = 0.075) comparedto previously reported Euphorbia species. The relatively high genetic variation in E. ebracteolata may be due toits long-lived regional distribution and to the outcrossed nature of the species. Low levels of genetic differen-tiation and the absence of unique alleles in E. ebracteolata populations suggest that Korean populations divergedrecently. This study does not support the recognition of var. coreana and for. magna as separate taxa, and sug-gests that they should be combined with E. ebracteolata. Keywords: Euphorbia ebracteolata, genetic variation, Euphorbiaceae 적요: 한국산붉은대극 9집단에대해 전분전기영동법을 이용하여 10개의 동위효소 유전자 좌위를 조사하였다. 붉은대극 집단은 기존의 대극속 식물과 비교해 볼 때 상대적으로 높은 집단 내 유전적 변이(A =2.2,P = 61.1, H